JPH05174676A - Power source change-over switch - Google Patents

Abstract

PURPOSE:To instantaneously carry out change-over switching even when a load is an OA apparatus that will be in a system-down condition in a long switching time by forming an electric power switch for selectively switching first and second power sources to connect them to the load, out of two contacts switched to one another complementarily, and of a fixed contact which will be a contact pair to the contacts. CONSTITUTION:A first contact 11 is provided between a first power source P1 and a load L, while a second contact 12 that is switched complementarily to the contact 11, is provided between a second power source P2 and the load L. It is indicated in the drawing that the contact 11 is closed and the contact 12 is opened. The contact 11 is composed of a contact pair of a first fixed contact 21 and a first moving contact 31, and the contact 12 is composed of a contact pair of a second fixed contact 22 and a second moving contact 32, while contact main parts 21M, 22M, 31M, 32M consisting of low resistance metals, and front end parts 21S, 22S, 31S, 32S consisting of high resistance metal, are provided on the contacts 21, 22, 31, 32, respectively, and the main body part and the front end part are connected together in an integrated manner. Front end parts are in contact with one another at first, and are opened in the last.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power switch for selectively switching between two different power supplies and connecting them to a load. From the viewpoint of improving reliability of power supply and effective use of energy, the recent trend is to provide a plurality of power sources, usually two systems. For example, in factories, buildings, etc. that have loads such as lighting equipment, electric motors, and various electric devices,
In addition to the conventional commercial power source as the first power source, a second power source using city gas, exhaust heat, or the like as an energy source is provided. A representative example of the second power source is a generator power source in a cogeneration system.

The present invention describes a power supply switch used to switch the power supply to a load from a first power supply to a second power supply and from a second power supply to a first power supply.

[0003]

2. Description of the Related Art FIG. 7 is a block diagram showing the principle of a conventional power switch. In the figure, the power source switching device includes a first contactor 1 connected between a first power source P1 and a load L, and a second power source P2.
And a load L, and a second contactor 2 that is opened and closed complementarily to the first contactor 1. Complementarily means that when the first contact 1 is closed (or opened), the second contact 2
Means open (or closed). So to speak, it constitutes a transfer switch. In the figure, the first and second contacts 1 and 2 are connected by a one-dot chain line to show that they open and close complementarily. The description of the electromagnetic coils and the like for driving the first and second contacts is omitted here.

FIG. 8 is a sequence diagram showing the operation of a conventional power supply switching device. In the figure, V _L represents a voltage waveform applied to the load L. Although _VL is actually an AC waveform, it is shown as a DC waveform in the figure for easy understanding. In the sequence of this figure, the first power source P1 is first connected to the load L, and then switched to the second power source P2 by the switching command (1), and after a while, the first power source is switched by the switching command (2). This shows a typical mode of returning to P1.

Before the switching command (1) is given, the first and second contacts 1 and 2 in the power switch are in the open / closed state as shown in FIG. Then, when the switching command (1) is given to the power source switching device, after a slight delay due to the sensitive time of the electromagnetic coil in the power source switching device, the first contact 1
Is from closed to open, and the second contactor 2 is from open to closed. After the switching instruction (2) is given, the state is completely opposite to the above.

The switching time at the time of opening and closing the first and second contacts 1 and 2 described above is shown as t1 in the figure, but this t1 is normally set to be 20 to 30 ms, which is considerably long. The reason is as follows. Referring to FIGS. 7 and 8, when the first contactor 1 goes from closed to open, an arc occurs between the contact pairs of the first contactor for a while immediately after the opening of the contact. If this arc is not extinguished, then the first contact 1 remains virtually closed,
Thereafter, if the second contactor 2 is closed, an arc short circuit will occur between the first power supply P1 and the second power supply P2. This short-circuit arc current is extremely large and causes damage. In this case, such an arc short circuit does not occur when the AC voltage phase of P1 and the AC voltage phase of P2 completely match. However, in reality, it is rare that the AC voltage phases of the two completely match at the time of power source switching, and there is a phase shift between the AC voltages of the two. This phase shift causes the above arc short circuit.

Therefore, generally, the time from the opening of the first contactor 1 (or the second contactor 2) to the closing of the second contactor 2 (or the first contactor 1) is sufficiently long. Then, the other contactor is closed after the arc at the time of opening the one contactor is completely extinguished. For this,
A switching time t1 of 20-30 ms is required.

[0008]

The above-mentioned 20-30 ms
For the load L, the switching time t1 of 1 corresponds to the time of power interruption (power failure). Usually, this kind of 20-30ms
Powering off for a certain period of time does not cause any trouble in a general electric light load or electric motor load. However, in recent years, many OA devices such as personal computers, workstations, and word processors have come to be included in the various electric devices described above. These OA devices most dislike power cutoff, and if the time is long, so-called system down occurs. In other words, these OA devices are allowed only a momentary power interruption. This instantaneous interruption is usually about 10 ms. Note that there are electric appliances other than the above-mentioned OA appliances that allow only such a momentary interruption. For example, it is a relay sequence control board having a self-holding function.

Thus, in the conventional power supply switching device,
If the load L includes an electric device that has a long switching time t1 and that allows only a momentary power interruption, a problem occurs that the normal operation of the electric device is disturbed. If the drive mechanism of the contactors 1 and 2 is simply adjusted so as to shorten the t1, this will cause a serious obstacle such as the above-mentioned arc short circuit between the power supplies.

Therefore, in view of the above problems, it is an object of the present invention to provide a power source switching device which does not cause an arc short circuit and can cope with a load which allows only instantaneous interruption.

[0011]

FIG. 1 is a block diagram showing the principle of a power source switching device according to the present invention. The power supply switching device according to the present invention has the configuration shown in the figure. Reference numeral 11 is a first contactor connected between the first power supply P1 and the load L, and 12 is a
The first contact 1 is connected between the second power source P2 and the load L.
It is a second contactor that opens and closes in a complementary manner to 1 (indicated by a chain line in the figure). In the figure, the first contact 11 is closed,
The case where the second contactor 12 is open is shown.

As shown in FIG. 1, the first contact 11 has a first contact.
It is composed of a fixed contact 21 and a first movable contact 31. The second contact 12 includes a contact pair of a second fixed contact 22 and a second movable contact 32. Further, the first and second fixed contacts 21, 22 and the first and second movable contacts 31, 32
Each of the contact points is composed of contact body portions 21M, 22M, 31M and 32M made of low resistance metal and tip portions 21S, 22S, 31S and 32S made of high resistance metal, respectively. Is joined to.

The opposite end portions 21S and 31S are opposed to each other.
And 22S and 32S, respectively, are arranged such that when the first and second contacts 11 and 12 are closed or opened, they start contacting with each other from the tip portions, or the tip portions are separated from each other lastly. There is.

[0014]

2 is a sequence diagram used for explaining the operation of the power supply switching device according to the present invention, and corresponds to FIG. 8 described above. When the switching command (1) is given, the first contactor 11 opens from closed to open, and generally, the voltage applied to the load L along the curve shown by the dotted line a1 in FIG. Waveform _VL falls rapidly. However, according to the present invention, in the process of the first movable contact 31 coming out of the first fixed contact 21, the contact body portions 21M and 31M (both of which have low electric resistance) and the tip portions 21S and 31S thereof (both of which have low electric resistance). With high electrical resistance), the following contact pattern → occurs sequentially.

21M + 31M (lowest resistance and “closed”) 21S + 31M (slightly higher resistance) 21S + 31S (highest resistance) The first contactor is “open” As a result, the first contactor is gradually added with current limitation. 11
Is opened, the voltage V _L can be lowered along the solid line b1 in FIG. 2 without generating an arc between the first fixed contact 21 and the first movable contact 31.

At the same time when the first contact 11 is opened, the second contact
The contactor 12 is closed. That is, the second movable contact 32
Enters the second fixed contact 22. In the process of this intrusion, the following contact is made between the contact main body portions 22M and 32M (both have low electric resistance) and the tip portions 22S and 32S (both have high electric resistance). The form → occurs sequentially.

The second contactor is “open” 22S + 32S (highest resistance) 22S + 32M (slightly lower resistance) 22M + 32M (lowest resistance and “closed”) As a result, the above-mentioned description of the first contactor 11 toward opening is given. In the contact form, even if an arc slightly remains between the first fixed contact 21 and the first movable contact 31, due to the high resistance in the contact form of the second contact 12 toward closing, this Can be significantly suppressed and an arc short circuit does not occur. Further, since the opposed tip end portions 22S and 32S start to contact each other before the contact main body portions 22M and 32M which are the original contact portions, as shown in FIG.
Where _L rises, in the present invention, V _L rises at an early timing as indicated by the dotted curve b2.

In the above description, the operation when the first contact element 11 is switched to the open state and the second contact element 12 is switched to the closed state (by the switching command (1)), but the switching command is reversed. When (2) is given, that is, the second contact 1
The same applies to the operation when 2 is switched to open and the first contactor 11 is switched to closed. After all, as is apparent from FIG. 2, the conventional switching time t1 (20 to 30 ms) is changed to t2 (1
It will be almost halved to 0 ms or less), and a high-speed power supply switching device will be realized.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 is a connection diagram of an embodiment according to the present invention, showing a case of a three-phase three-wire system. Of course, it is also applicable to the case of single-phase or three-phase four-wire system. A single-phase load such as an OA device in the load L is connected between any two phases. In this figure, the same components as those described above are designated by the same reference numerals or symbols. Further, R, S, T and U, V, W are symbols representing the phases.

FIG. 4 is a view showing another shape of the contact,
The first contact 11 is shown as an example. The same applies to the second contact 12 as well. The shape of FIG. 4 forms a so-called tulip-shaped contact. Even if such a tulip-shaped contact is used or a wedge-shaped contact is used, the voltage waveform (b1, b1 shown in FIG.
b2) is obtained.

FIG. 5 is a diagram showing the movement of the contactor and its equivalent circuit. As shown in the equivalent circuit of this figure, when the contact opens, the resistance changes by 1 step → resistance 2 steps → "open", and when it closes, the resistance changes by 2 steps → resistance 1 step → "closed" do. This suppresses the arc generated between the fixed contacts (21, 22) and the movable contacts (31, 32). Moreover, since the tip portion (S) is added to the contact portion main body (M) which is the original contact element, the first contact element 11
Since the (second contactor 12) closes at an earlier timing than the conventional one and the second contactor 12 (first contactor 11) opens at a later timing than the conventional one, so-called early closing / late opening is realized. , As shown by t2 (<t1) in FIG. According to the experiment, t1≈5 ms is achieved. Note that t1 is generally 20 to 30 ms.

FIG. 6 is a view showing the structure of a general contactor. In this figure, the two contacts 11 and 12 are opened and closed complementarily by, for example, a seesaw type crank mechanism (insulator). However, in the figure, the seesaw type crank mechanism is represented by a one-dot chain line for simplification. The center fulcrum (crankshaft) of the seesaw is indicated by 41, and the two contacts 11 and 12 move up and down in the direction of the solid arrow or the direction of the dotted arrow shown. This vertical movement is caused by electromagnetic coils MG1 and M1.
Made by G2.

Returning to FIG. 1, the contact body portions 21M and 22
M, 31M, and 32M were formed by using a copper material (Cu) as a main material, similar to a normal contactor. Preferably the copper material is coated with a silver-cadmium alloy. This is for exhibiting arc resistance and maintaining good conductivity. on the other hand,
Tip portions 21S, 22S, 31S forming the point of the present invention
And 32S were formed by using a stainless steel material (SUS) as a main material. The tip made of this stainless steel material is mechanically fixed to one end of the contact body.

Alternatively, one end of the contact body may be covered with a stainless material. The high resistance metal is not limited to the stainless steel material, but a known material such as nichrome material can be used.

[0025]

As described above in detail, according to the present invention, 2
A power supply switch suitable for connecting a load including an OA device that causes a system down in a long power supply switching time of 0 to 30 ms, that is, a power supply switch capable of completing switching by a momentary power interruption.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of a power supply switching device according to the present invention.

FIG. 2 is a sequence diagram used for explaining the operation of the power supply switching device according to the present invention.

FIG. 3 is a connection diagram of an embodiment according to the present invention.

FIG. 4 is a view showing another shape of the contact.

FIG. 5 is a diagram showing movement of a contact and its equivalent circuit.

FIG. 6 is a diagram showing a structure of a general contactor.

FIG. 7 is a principle configuration diagram of a conventional power supply switching device.

FIG. 8 is a sequence diagram showing an operation of a conventional power supply switching device.

[Explanation of symbols]

 11 ... 1st contactor 12 ... 2nd contactor 21 ... 1st fixed contact 22 ... 2nd fixed contact 31 ... 1st movable contact 32 ... 2nd movable contact 21M, 22M, 31M, 32M ... Contact main-body part 21S, 22S , 31S, 32S ... Tip P1 ... First power supply P2 ... Second power supply L ... Load

Continued Front Page (72) Inventor Tomio Sekine 3-8-13 Yoga, Setagaya-ku, Tokyo

Claims (2)

[Claims] 1. A first power source (P1) and a second power source (P1)
A power source switching device for selectively switching 2) to connect to a load (L), the power source switching device being connected between the first power source and the load, and
A first contactor (11) formed of a contact pair of a fixed contact (21) and a first movable contact (31), connected between the second power source and the load, and complementary to the first contactor. To the second fixed contact (2
2) and a second movable contact (32) consisting of a pair of contacts
A contact body (12), wherein the first and second fixed contacts and the first and second movable contacts each have a contact body (21M, 22M, 31M, 32M) made of a low resistance metal. The tip portions (21S, 22S, 31S, 32S) made of high-resistance metal are integrally joined, and the tip portions facing each other (21S, 31S; 22S, 3S)
2S), when the first and second contactors are closed or opened, start contacting from the tip end portions,
Alternatively, the power supply switching device is characterized in that the tip portions are arranged so as to be finally separated from each other. 2. The contact portion body made of the low resistance metal,
The power source switching device according to claim 1, wherein the main material is a copper material, and the tip portion made of the high resistance metal is a stainless material as a main material.